The present invention relates generally to fluid medication delivery systems and associated infusion pumps and deals more particularly with a medication delivery system having a programmable, self-contained, ambulatory pump unit (APU), and communication system for retrieving information from and sending information to the APU and for communication with a computer through a communication unit which interfaces the APU to a host computer. The present invention relates further to the APU having a replaceable and disposable fluid infusion pumping system and a computer controllable micro infusion pump (MIP) for supplying desired predetermined volumes of medication or nutrients in accordance with a preprogrammed schedule.
Increased health costs, longer life spans due to improved medical diagnostics and drugs, and improved home health care and parenteral administration of medication has greatly expanded the need and demand for accurate, reliable, easy to use, low cost and virtually foolproof healthcare fluid administration systems. It is desirable that such fluid administration systems not restrict the mobility of a user or be so obtrusive as to interfere with normal day-to-day activities. It is also desirable that such fluid delivery systems be user-friendly, simple, safe-to-use, and minimize involvement of professional healthcare workers in order to be cost effective.
Drawbacks associated with known medication delivery systems in general relate to the type of pumps used to deliver the fluid, the control of the pump and lack of feedback information relating to the status of the user. All known pumps have similar problems which render them unsuitable or less than desirable for use in the safe and accurate delivery of fluid. Add-on devices and apparatus are generally required to be used with known pumps and delivery systems to assure safe operation and to cause failures to be detectable and responded to with proper reaction modes. One general class of such pumps are for example, peristaltic type pumps the operation of which is generally well known. Typically, a flexible plastic tube passes through the peristaltic pump and carries a fluid from a supply reservoir to an outlet which may be connected to a catheter for infusion into the patient. The wall of the tube is successively squeezed and released along a portion of the tube between the surface of a cam and a pressing surface in contact with the exterior surface of the tube to force the fluid within and along the interior of the tube in an amount approximately equal to the volume displaced by the cam surface in contact with the tube. The fluid is drawn into the pump from the reservoir and pressurized to flow through the outlet by the action of the rotating cam rolling over the exterior surface of the tube to infuse a recipient.
A disadvantage of known peristaltic type infusion pumps is that they are driven by a rotary motor and may fail powered, that is, with a communication path established through the pump which causes the fluid from the supply to be continuously connected to the output and therefore to the body of the recipient being infused. Such a failure mode presents a potential harm to the recipient in that an overdose or excessive medication may occur unless devices or apparatus are added to the pump to automatically preclude such action to isolate the supply of fluid to the output.
Another disadvantage of known peristaltic type infusion pumps is that it is difficult to accurately control the volumetric amount of fluid that can be incrementally delivered due to differences in the area of expansion and contraction, tolerances, wear, and pliability of the flexible tube carrying the fluid or medicant when the contact area of the cam rolls over the exterior surface of the tube.
A further limitation of known peristaltic type pumps is the inability to automatically operate the pump at predetermined pressures. Generally, peristaltic type pumps will pressurize the infused fluid to the limits of the motor capability unless additional devices are added to prevent excess fluid pressurization.
Another disadvantage generally associated with known peristaltic type pumps is their complexity, large number of parts, and relatively large size which inhibits or restricts mobility of the user and accordingly, the ambulatory infusion of fluid to a recipient is obtrusive or otherwise made not convenient.
A further disadvantage is the supply of fluid to peristaltic type pumps is generally interfaced by a complex pumping mechanism and add-on devices or apparatus which in turn may be misassembled or which may otherwise malfunction thereby increasing the chance of affecting the safe operation of the infusion unit resulting in yet further additional safety devices to be required. Consequently, in order to render the infusion unit foolproof as practical the installation of the add-on devices or apparatus greatly increases the cost and complexity, reduces reliability, increases the size of the unit and generally renders the unit unsuitable for convenient ambulatory infusion of a user.
The above and other disadvantages of known infusion pumps and fluid delivery systems are generally overcome or mitigated with the present invention which provides a computer controllable, positive displacement MIP to accurately and reliably dispense predetermined volumes of medication or nutrient fluid. The MIP and fluid delivery system of the present invention provides medication or nutrient fluid delivery in accordance with programmed infusion schedules which may be altered, modified, monitored or input from a communication unit locally or from a remote location. The fluid delivery system of the present invention is particularly suited for ambulatory infusion due to the small size of the APU and because the medication or nutrient fluid reservoir may be contained within the unit to provide direct and intimate connection to the MIP. The APU can also accommodate larger sized fluid reservoirs that cannot fit within the APU.
The APU is also suitable for use in multi-infusion applications which mix multiple medicant or nutrient fluids during programmed administration. The multi-infusion APU is also suitable for use in conjunction with preprocessing, interprocessing, and postprocessing fluids for multiple medicant profiles using simultaneous or sequential administration.